feat: add mail/v2

mail/v2/docker/mda-dovecot

@@ -0,0 +1,9 @@
+FROM alpine:3.15
+
+RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.ustc.edu.cn/g' /etc/apk/repositories  \
+    && apk add dovecot-pgsql dovecot-lmtpd \
+    && rm -rf /var/cache/apk/*
+
+EXPOSE 143 993
+
+CMD ["/usr/sbin/dovecot", "-F"]